'\" te
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.TH CLOCK 3C "Jul 24, 2002"
.SH NAME
clock \- report CPU time used
.SH SYNOPSIS
.LP
.nf
#include <time.h>

\fBclock_t\fR \fBclock\fR(\fBvoid\fR);
.fi

.SH DESCRIPTION
.sp
.LP
The \fBclock()\fR function returns the amount of CPU time (in microseconds)
used since the first call to \fBclock()\fR in the calling process. The time
reported is the sum of the user and system times of the calling process and its
terminated child processes for which it has executed the \fBwait\fR(3C)
function, the \fBpclose\fR(3C) function, or the \fBsystem\fR(3C) function.
.SH RETURN VALUES
.sp
.LP
Dividing the value returned by \fBclock()\fR by the constant
\fBCLOCKS_PER_SEC\fR, defined in the <\fBtime.h\fR> header, will give the time
in seconds.  If the process time used is not available or cannot be
represented, clock returns the value \fB(clock_t) \(mi1\fR.
.SH USAGE
.sp
.LP
The value returned by \fBclock()\fR is defined in microseconds for
compatibility with systems that have CPU clocks with much higher resolution.
Because of this, the value returned will wrap around after accumulating only
2147 seconds of CPU time (about 36 minutes).
.SH ATTRIBUTES
.sp
.LP
See \fBattributes\fR(7) for descriptions of the following attributes:
.sp

.sp
.TS
box;
c | c
l | l .
ATTRIBUTE TYPE	ATTRIBUTE VALUE
_
Interface Stability	Standard
_
MT-Level	MT-Safe
.TE

.SH SEE ALSO
.sp
.LP
.BR times (2),
.BR popen (3C),
.BR system (3C),
.BR wait (3C),
.BR attributes (7),
.BR standards (7)
